When a device's function set has been defined, additional test cases can be created by adding or modifying existing test-case scripts. Thus, adding new test cases for an existing device requires knowledge of that device and an flat file editor. Using DDTT's scripting capabilities, new test cases can be quickly developed to cover any "holes" identified in existing test "buckets".

In addition to device-specific functions, DDTT test case developers can use all of the functions described in Script Utility Functions.

The interface provided for the test case script writer is procedural. Commands are executed top-to-bottom within a given test-case thread.

Built-in generic functions are provided for creating test case scripts. Generic functions are independent of any device under test. Syntax of these functions is the same across all DDTT device interfaces.